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Setting Up Active Directory

  6 minute read.

Last Modified 2022-08-15 14:57 -0400

The Active Directory (AD) service shares resources in a Windows network. AD provides authentication and authorization services for the users in a network. This eliminates the need to recreate the user accounts on TrueNAS.

Domain users and groups in local ACLs are accessible after joining AD. Setting up shares acts as a file server.
Joining an AD domain configures the Privileged Access Manager (PAM). This allows domain users to log on via SSH or authenticate to local services.

It is possible to configure AD services on Windows. Or on Unix-like operating systems running Samba version 4.

To configure a connection, you need to know the following items:

  • Determine the Active Directory domain controller domain.
  • Make sure you have the account credentials for that system.

Preparation

Preparing the following before configuring Active Directory helps ensure the connection process.

Confirm that name resolution is functioning. Go to Shell and use ping to check the connection to the AD domain controller.

ShellDomainControllerPing

The ability to send and receive packets without loss verifies the connection. Press Ctrl + C to cancel the ping.

Another option is to use the command host -t srv _ldap._tcp.domainname.com. This checks the network SRV records and verifies DNS resolution.

If the ping fails, go to Network > Global Configuration. Update the DNS Servers and Default Gateway settings. Enter more than one value in Nameserver for the AD domain controllers. This helps DNS queries for the required SRV records succeed. Domain controllers are not always available. Using more than one name server helps maintain the AD connection in these instances.

Active Directory relies on Kerberos, a time-sensitive protocol. During the domain join process, the AD domain controller with the PDC Emulator FSMO Role is added as the preferred NTP server.

You can change NTP server settings in System > NTP Servers if necessary.

In a default AD environment, the local system time must be in sync with the AD domain controller time. Their times cannot differ from each other by more than 5 minutes. Use an external time source when configuring a virtualized domain controller. TrueNAS creates an Alert if the system time gets out of sync with the AD domain controller time.

The following options apply to time synchronization in TrueNAS:

  • Go to System > General and make sure the value in Timezone matches the AD Domain Controller.

SystemGeneralTimezoneOptions

  • Select either local time or universal time in the system BIOS.

Connect to the Active Directory Domain

To connect to Active Directory, go to Directory Services > Active Directory. Enter the AD Domain Name and account credentials. Select Enable to attempt to join the AD domain immediately after saving the configuration.

DirectoryServicesActiveDirectoryExample

The preconfigured defaults are generally suitable. Advanced options are available for fine-tuning the AD configuration. Click ADVANCED OPTIONS to access extra options.

Click REBUILD DIRECTORY SERVICE CACHE to resync the cache if it becomes out of sync. Or if fewer users than expected are available in the permissions editors.

After configuring the Active Directory service, there can be a delay. TrueNAS can take a few minutes to populate the AD information. To check the AD join progress, open the Task Manager in the upper-right corner. TrueNAS displays any errors during the join process in the Task Manager.

When the import completes, AD users and groups become available. These have basic dataset permissions or an Access Control List (ACL). Enabled is the default status for the TrueNAS cache.

Joining AD adds default Kerberos realms and generates a default AD_MACHINE_ACCOUNT keytab. TrueNAS automatically begins using this default keytab. TrueNAS removes any administrator credentials stored in the TrueNAS configuration file.

The recommendation is to use SFTP over FTP. But joined systems do allow FTP access. Keep these caveats in mind:

  • Authentication uses DOMAIN\username as the user name by default.
  • A user home directory needs to exist before joining.
  • You cannot add an AD user to the FTP group. Enable local user auth for FTP instead.
  • An existing samba homes share created in the GUI is set as the template homedir for AD users. This means that AD user home directories are set inside that path. Proper permissions are vital.
  • There are no guarantees about how proftpd handles ACLs.
  • AD users can have populated homedir information in their LDAP schema. The admin (or pam_mkhomedir) must ensure that these paths exist.
  • When the admin is pulling home directories from their LDAP schema, take an extra step of caution. Ensure that users aren’t writing files to the boot device.

Troubleshooting

Resync the cache if it becomes out of sync. Or if fewer users than expected are available in the permissions editors. Go to Directory Services > Active Directory > REBUILD DIRECTORY SERVICE CACHE.

If you are using Windows Server with 2008 R2 or older, try the following options:

Create a Computer entry on the Windows server Organizational Unit (OU). When creating this entry, enter the TrueNAS host name in the name field. Make sure it is the same name as the one set in the Hostname field in Network > Global Configuration. Must match the NetBIOS alias from Directory Services > Active Directory > Advanced Options.

You can go to the Shell and enter various commands to get more details about the AD connection and users:

  • AD current state: midclt call activedirectory.get_state.
  • Details about the currently connected Lightweight Directory Access Protocol (LDAP) server: midclt call activedirectory.domain_info | jq. Example: 
    truenas# midclt call activedirectory.domain_info | jq
{
  "LDAP server": "192.168.1.125",
  "LDAP server name": "DC01.HOMEDOM.FUN",
  "Realm": "HOMEDOM.FUN",
  "Bind Path": "dc=HOMEDOM,dc=FUN",
  "LDAP port": 389,
  "Server time": 1593026080,
  "KDC server": "192.168.1.125",
  "Server time offset": 5,
  "Last machine account password change": 1592423446
}
  • View AD users: wbinfo -u. To see more details about a user, enter getent passwd DOMAIN\\<user>. Replace <user> with the desired user name. With the TrueNAS cache enabled wbinfo -u can show more users than appear to be available when configuring permissions. Go to Directory Services > Active Directory and increase the AD Timeout value.
  • View AD groups: wbinfo -g. To see more details, enter getent group DOMAIN\\domain\ users.
  • View domains: wbinfo -m.
  • Test AD connection: wbinfo -t. A successful test shows a message similar to checking the trust secret for domain YOURDOMAIN via RPC calls succeeded.
  • User connection test to an SMB share: smbclient '//127.0.0.1/smbshare -U AD01.LAB.IXSYSTEMS.COM\ixuser, replacing 127.0.0.1 with your server address, smbshare with the SMB share name, AD01.LAB.IXSYSTEMS.COM with your trusted domain, and ixuser with the user account name for authentication testing.

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